1 files changed, 38 insertions, 1 deletions
diff --git a/src/2016/day22/aoc.cpp b/src/2016/day22/aoc.cpp
index f115778..b4201e3 100644
--- a/src/2016/day22/aoc.cpp
+++ b/src/2016/day22/aoc.cpp
@@ -1,6 +1,43 @@
 #include "aoc.h"
+#include <algorithm>
 
 namespace aoc2016 {
 
-std::pair<int64_t, int64_t> day22(line_view) { return {0, 0}; }
+// A, B
+bool is_pair(const grid_node& n1, const grid_node& n2) { return n1.s[1] > 0 && n2.s[2] >= n1.s[1]; }
+
+void find_pairs(size_t x, const std::vector<grid_node>& ns, int* count) {
+  if (x < ns.size() - 1) {
+    auto& n1 = ns[x];
+    for (size_t i = x + 1; i < ns.size(); i++) {
+      auto& n2 = ns[i];
+      if (is_pair(n1, n2)) {
+        *count += 1;
+      }
+      if (is_pair(n2, n1)) {
+        *count += 1;
+      }
+    }
+    find_pairs(x + 1, ns, count);
+  }
+}
+
+std::pair<int64_t, int64_t> day22(line_view file) {
+  std::vector<grid_node> ns;
+
+  per_line(file, [&ns](line_view lv) {
+    if (*lv.line == '/') {
+      ns.emplace_back(lv);
+    }
+    return true;
+  });
+
+  // std::sort(ns.begin(), ns.end());
+  // for (auto& n : ns) {
+  //   n.print();
+  // }
+  int count{0};
+  find_pairs(0, ns, &count);
+  return {count, 0};
+}
 } // namespace aoc2016